- 學位論文
應用切換式電容器與靜態同步補償器改善微電網之風場電壓穩定度
Voltage Stability Improvement Research of Wind Farm Equipped Micro-Grid with Switched-Capacitor and Static Synchronous Compensator
摘要
再生能源搭配微型電網為目前全球電力系統發展趨勢。台灣的風力機組主要集中於本島沿海地區，距離台電系統負載中心相當遙遠，使具風場的微電網系統結構與台電系統併網時風場容易受系統擾動所影響，若發生嚴重事故如線路故障時可能導致風場電壓無法維持穩定而電壓崩潰。 本文探討微電網內風場於系統變動時之電壓穩定度，以MATLAB/Simulink/SimPowerSystems建立一與市電併網之鼠籠式感應發電機所構成的風場以及區域負載所組成的微型電網，模擬當區域負載變動、系統故障或馬達啟動時風場的電壓變動，並於風場電壓崩潰時利用切換式電容器與靜態同步補償器以提升電壓穩定度。 依本文理論分析與模擬結果顯示，傳輸線路阻抗越大風場所能承受的負載極限越低，並聯電容可增加風場的承載能力；而閘流體控制切換式電容(TSC)於區域負載變動時亦可有效將風場電壓控制於0.9~1.1標么之間，提升穩態之電壓穩定度。而當系統發生長時間故障或馬達啟動等暫態擾動時，切換式電容器(SC)與靜態同步補償器(STATCOM)皆可有效提升風場電壓，其中切換式電容器(SC)控制較簡單、價格經濟，而靜態同步補償器(STATCOM)具即時補償、平滑輸出虛功之特性，兩者皆可應用於系統較弱的偏遠地區風場電壓之改善。
並列摘要
Renewable energy generation system and micro-grids received much attention in recent years.In Taiwan,wind farms are usually installed in coastal areas faraway from existing subtations.If micro-grids equipped with wind farms are connected to power systems,substantial variations in generator terminal voltages will be observed when there is a fault in the power system. Severe faults in the system may ever cause voltage collapse and generator instability. The purpose of this thesis is to investigate terminal voltage stability of wind generators when the power system is subjected to disturbances. MATLAB/Simulink/SimPowerSystems was used to perform digital simulations on the wind generator system subjected to disturbances. The grid-connected micro-grid simulation model included the area loads and the wind farm composed of squirrel-cage induction generators. Results from theoretical analyses and digital simulations indicate that ,as the transmission line impedence increases,the load limit for the wind farms will decrease.Shunt-capacitors(SCs) can be used to improve the terminal voltage stability of wind farms.In addition,thyristor switched capacitors(TSC) can be used to effectively control the voltage magnitude within the range from 0.9 to 1.1p.u. when the area load change with time.On the other hand,when there is a disturbance such as system fault or motor starting,SCs and static synchronous compensators(STATCOMs) are useful for the enhancement of generator terminal voltages. Therefore, SCs ,which are simple and inexpensive,and STATCOMs ,which are capable of provide rapid and smooth compensation can be employed to provide voltage regulations and reactive power compensations for a remote micro grid with wind farms in Taiwan.